package com.fjb.common.utils;

import java.security.MessageDigest;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.SortedMap;

/**
 * md5 工具类
 */
public class MD5Util {
	
	 	private static final String hexDigits[] = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };  
		  
		private static String byteArrayToHexString(byte b[]) {  
	        StringBuffer resultSb = new StringBuffer();  
	        for (int i = 0; i < b.length; i++) {
	            resultSb.append(byteToHexString(b[i]));  
	        }
	        return resultSb.toString();  
	    }  
	  
	    private static String byteToHexString(byte b) {  
	        int n = b;  
	        if (n < 0) { 
	            n += 256;
	        }
	        int d1 = n / 16;  
	        int d2 = n % 16;  
	        return hexDigits[d1] + hexDigits[d2];  
	    }  
	  
	    public static String MD5Encode(String origin, String charsetname) {  
	        String resultString = null;  
	        try {  
	            resultString = new String(origin);  
	            MessageDigest md = MessageDigest.getInstance("MD5");  
	            if (charsetname == null || "".equals(charsetname)) { 
	                resultString = byteArrayToHexString(md.digest(resultString  
	                        .getBytes())); 
	            }else {  
	                resultString = byteArrayToHexString(md.digest(resultString.getBytes(charsetname)));
	            }
	        } catch (Exception exception) {  
	        }  
	        return resultString;  
	    }  
	  
	      
	      
	    /** 
	     * 创建md5摘要,规则是:按参数名称a-z排序,遇到空值的参数不参加签名。 
	     */  
		public static String createMD5Sign(SortedMap<String, String> signParams,String paykey) {  
	        StringBuffer sb = new StringBuffer();  
	        Set<Entry<String, String>> es = signParams.entrySet();  
	        Iterator<Entry<String, String>> it = es.iterator();  
	        while (it.hasNext()) { 	 
	            @SuppressWarnings("rawtypes")
				Map.Entry entry = (Map.Entry) it.next();  
	            String k = (String) entry.getKey();  
	            String v = (String) entry.getValue();  
	            if (null != v && !"".equals(v) && !"sign".equals(k)  
	                    && !"key".equals(k)) {  
	                sb.append(k + "=" + v + "&");  
	            }  
	        }  
	        sb.append("key=" + paykey);  
	        String sign = MD5Encode(sb.toString(), "UTF-8").toUpperCase();  
	        return sign;  
	    }  

}
